I'm having trouble with crazy gauges on my ´95 Bonneville SSE 3.8 (no *.*.). I'm suspecting the cooling system of being the source. However, it seems a bit far fetched. I need to know if my thesis is plausible.

I've read most of the threads on the subject, but the descriptions doesn't fit my situation entirely. The craziness is intermittent, but with certain a pattern. I've had it for about one year now, and found out the following:

1.When the engine is cool, there is no problem.
2.The crazy gauges (computer and whole cluster, except speedometer and rpm) appears when the temperature is rising to 200 degrees F.
3.If I continue to drive the problems seem to go away after a couple of minutes of flash and ding ding. Now the temperature is slight above 200 degrees.

The following might also be clues.

The problem seems to appears more often in uphills and low speeds.
In cold damp weather the problem seems smaller or goes away completely
The computer almost always start to indicate low cooling fluid when the craziness starts.
The temperature inside the car does not affect the problem. Smashing the dashboard, fusebox or the cluster does not affect the problem.
I've have a new battery and I've checked the alternator. The battery maintains about 14 volts on the volt meter.
I've had a cooling fluid leak before a got crazy gauges. I let the repair shop to pressurize the cooling system, but they claimed there was no leak. Then I bought some ”cooler cement” that claimed to be able to seal the leak. It did, but the cooling water is now dark brown. The crazy gauge problem appeared a few weeks later when a left the car undriven for a week or so.
I've might also have a ground problem. Sometimes the car seem to lose electrical power for a split second. However I don't think it'* related. My repair shop also found a very suspicious blue fuse around slot 9 (don't know the exact position, but it might have been the suspension level fuse ). The fuse was shortcuted on purpose .


Best regards,

Sebastian Vidovic
Stockholm/Sweden

Hello Sebastin and welcome..

Does your carpet seem to be wet?

Take a look at this article and check the grounds. A common issue with the Bonneville is water related or corrosion.

https://www.gmforum.com/t278980/

I second that. Sounds like a corrosion problem. Being a older car, you may want to try these two tests as well. Although the ground bus is the most likely cause, it'* still worth checking.

https://www.gmforum.com/t279492/

https://www.gmforum.com/t279494/

I had crazy gauges in my 95 SSE until I pulled my cluster apart and replaced the right three gauges circuit board. Fixed the problem.

Is your right three gauges the ones that are going wacky?

Thank you for all answers! This site is really helping me a lot over time.

Somehow I don't think it the cluster itself. All gauges, including the compass and the computer and the light-level, are whacky. The whole cluster restarts itself, except for the speedometer and the rpm. And it is somehow related to the temperature for sure.

I'll think my first option is to check out the ground as suggested. The floor is not wet, but there is certain dampness in the climate with snow and fog. This may very well be the reason, but still I wonder over the intermittent behavior related to engine temperature.

Is there any chance that a clogged cooling fluid sensor can trigger this behavior? There was a post on crazy gauges, where the guy claimed that he found oil in the cooling fluid.

Here in Sweden the Bonneville is an extremely rare car. Not many repair shops are willing to address electrical problems, and model specific spare parts are hard to get, and quite expensive. So if I can't fix it myself with a cheap spare part, I'll settle with disconnecting the dinger or installing a switch on the fuse that controls the cluster.

It sounds to me like a circuit board has become de-laminated. As the care heats up, the circuit board affected warms up and expands. As it expands then electrical contact points become separated and connections are lost. This happened allot in the computer world with a certain version of a PC mother board. It was called a 'cold solder' problem and it did not presetn itself until the PC warmed up - then suddenly shut down.